In 1975, a cohort of nearly 2,800 people who were 65 years of age and free of dementia provided a basis for an incident study of dementia, as well as for Alzheimer's disease. This cohort was followed for almost 29 years and its sentinel findings included a significantly higher lifetime risk for both Alzheimer's and dementia in women compared to men. The estimated lifetime risk was nearly one in five for women compared to one in ten for men. In addition to the higher lifetime risk in women, expectancy of longer life and the aging of the "baby boomers" combined with improved healthcare is expected to increase the number of Americans who will reach 85 years of age or more. It is very clear that as the age increases, so does the incidence of Alzheimer's and other forms of dementia.